1. Field of the Invention
The present invention relates to an image forming apparatus and a process cartridge.
The image forming apparatus is defined here as the one that forms an image on a recording medium. For example, the image forming apparatus includes an electrophotographic copying machine, an electrophotographic printer (a light emitting diode (LED) printer and a laser beam printer), an electrophotographic facsimile machine, and an electrophotographic word processor using an electrophotographic image forming process.
The recording medium is the one on which the image is formed, and refers to a recording sheet and an over head projector (OHP) sheet, for example.
The process cartridge refers to the one that can be attached to and detached from a main body of the image forming apparatus.
2. Description of the Related Art
Heretofore, the image forming apparatus has adopted a process cartridge system which integrates an electrophotographic photosensitive member (hereinafter referred to as photosensitive drum) as an image carrying member with a process unit acting thereon, and which can be attached to and detached from the main body of the image forming apparatus (hereinafter referred to as apparatus main-body). The process cartridge system can improve operability because the maintenance of the apparatus can be performed by a user itself.
The process cartridge adopts a corona discharge system or a roller charging system as an example of a charging unit (a charging member or a charging device) for charging the photosensitive drum. The corona discharge system uses a charging wire to generate corona discharge for uniformly discharging a surface of the photosensitive drum. A large number of configurations have been proposed in which a cleaning member is provided as a means of periodically cleaning dirt attached on the charging wire and is moved in a longitudinal direction along the charging wire.
However, if the cleaning member is left in an image forming area in the longitudinal direction at the time of forming an image, the cleaning member covers the wire. In other words, the cleaning member inhibits the wire from charging the photosensitive drum to cause an image defective due to a charging defective. Japanese Patent Application Laid-Open No. 2002-304046, for example, discusses a configuration, as a means of solving the above problem, in which leaving the cleaning member in the image forming area prevents the process cartridge from being attached to the apparatus main-body.